Closing actuator for sheet material clamp

ABSTRACT

A closing actuator for a sheet material clamp has a first threaded orifice in a lower clamping jaw with a threaded interior wall, a second non-threaded orifice formed in an upper clamping jaw which has a retention groove formed around the non-threaded interior wall; and an actuating screw with a retention shoulder formed between the head and the threaded shank, such that the threaded shank mates with the threaded first orifice in the lower clamping jaw and the retention shoulder snaps into the retention groove, thereby capturing the actuating screw in the upper clamping jaw when threaded into the lower clamping jaw. The second orifice may be a slotted or oval shape to allow the actuating screw to pass through the upper jaw at an angle other than perpendicularly to the upper jaw as the jaws assume various angles of relationship to each other during clamp closing and opening.

FIELD OF THE INVENTION

The invention generally relates to devices and methods for attachingcords, ropes, and bungees to tarps, and more generally to devices forclamping sheet materials.

BACKGROUND OF INVENTION

There is a common need to attach a retention means such as a rope orbungee cord to a tarp in order to secure it in place, such as over aload on a trailer of a truck or over the top of a tractor or boat toprotect it from the elements.

Possibly the most common attachment means for such a tarp are grommetswhich are installed through the tarp material. Grommets can, however,present a hazard to damaging the fine finish of a covered item, such aspaint on an automobile, and are subject to tearing out. And, grommetsmay or may not be pre-placed at the best points of securing a tarp.Further, not all tarps are provided with grommets, and installing agrommet by an end-user requires special tools and supplies.

There is a wide variety of tarp clamps which essentially pinch or cliponto an edge of a tarp. Most are constructed of plastic, metal, or acombination of plastic and metal, and have some sort of means foropening the clamp, and then reclosing the clamp after the tarp or sheetmaterial has been received into its clamping jaws. These types ofdevices are relatively inexpensive, can be positioned almost anywherealong the edge of a tarp as needed, and can be easily removed andre-used without a need for special tools or supplies.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION

A closing actuator for a sheet material clamp has a first threadedorifice in a lower clamping jaw with a threaded interior wall, a secondnon-threaded orifice formed in an upper clamping jaw which has aretention groove formed around the non-threaded interior wall; and anactuating screw with a retention shoulder formed between the head andthe threaded shank, such that the threaded shank mates with the threadedfirst orifice in the lower clamping jaw and the retention shoulder snapsinto the retention groove, thereby capturing the actuating screw in theupper clamping jaw when threaded into the lower clamping jaw. The secondorifice may be a slotted or oval shape to allow the actuating screw topass through the upper jaw at an angle other than perpendicularly to theupper jaw as the jaws assume various angles of relationship to eachother during clamp closing and opening.

BRIEF DESCRIPTION OF THE DRAWINGS

The description set forth herein is illustrated by the several drawings.

FIGS. 1 a and 1 b illustrate perspective views of a prototype tarp clampaccording to the present invention.

FIG. 2 provides an exploded view of the embodiment of FIGS. 1 a and 1 b.

FIG. 3 sets forth details of an embodiment of the clamp of FIGS. 1 a and1 b in which more details of a preferred mechanism to install andcapture the actuating screw are shown.

FIGS. 4 a and 4 b illustrate an optional aspect of the clamping surfacesincluding a top view and a cut-away view, respectively, in which theclamping surfaces are pre-loaded during the closing process.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S) OF THE INVENTION

The inventors of the present invention have realized several problemswith the existing collection bins and bags in the art. Firstly, grommetsare not end-user friendly if they are positioned in less-than-optimalpositions, if they tear out, if they present a damage hazard to acovered item, or if they need to be installed.

Further, some tarp clamps present sharp edges to the tarp material.These clamps provide linear grooves or notches in their clamping areawhich may be of zig zag or tooth-like shapes when viewed in a crosssection. When these clamps are installed on the edge of a tarp, thegrooves or notches are oriented generally parallel to the edge of thetarp material. If a rope or cord is attached to the clamp and then therope is pulled at an angle other than perpendicular to the direction ofthe grooves or notches (e.g. other than perpendicular to the edge of thetarp), then a rotational force (twisting) is applied by the clamp'sgripping area to the surface and through the thickness of the tarp. Thiskind of force may be applied as the cord is attached, if the departureangle of the cord is other than perpendicular to the edge of the tarp,and this kind of force may be applied dynamically due to pressures onthe tarp caused by wind and by shifting of the items under the tarp.Such repeated twisting eventually can lead to the sharp or harsh edgespresented by the clamping surfaces to tear into and damage the tarp.This damage can cause failure of the tarp to keep rain and dust off thecovered items, and may cause the clamp to tear free in more severecases.

Therefore, the present inventors have realized that the clampingsurfaces of tarp clamps need certain improvements for both performanceand reliability with respect to twisting and pulling forces which can beapplied by various securing and tie-down methods during practical use.

Additionally, the present inventors have realized that the variousmechanisms used to secure tarp clamps in their closed position havecertain shortcomings. Some which use a screw to actuate them may notallow the clamp to be opened all the way for cleaning or for grippingvery thick sheets of material, and some provide the two clamping jaws ina single, integral piece of plastic which cannot be disassembled. Someof these designs also allow the screw to be easily withdrawn fully,leading to the possibility of losing the screw if a user is adjusting orinstalling a clamp along a roadside, in inclement weather, etc. Stillothers use a sort of slide lock or ratcheting lock which can be easy tooperate, but may not be as secure and may not transmit as great ofclamping force as the screw-operated designs. And, the slide lock andratcheting lock designs may wear at certain points to become lesseffective over their useful lifespans.

Therefore, the present inventors have also realized that there is anunmet need in the art for an improved clamp actuating means which isless likely to be lost, which provides full clamping strength, and whichperforms consistently over the full lifecycle of the device.

Referring now to FIG. 1 a, which shows a prototype (100) of a sheetmaterial clamp according to the present invention. This view shows aclamp in an assembled state in an open position, ready to receive asheet material such as a tarp. It has three components: a top jaw member(101), a lower jaw member (102), and an actuating screw (104) receivedin a first orifice (108 b). In this prototype, which was designed andfabricated using a three-dimensional printer, the two jaws are realizedas separate and separable pieces joined by a hinge (103). In someembodiments, they may be initially separate pieces which are permanentlyadjoined through snapping, gluing, welding, etc., and in otherembodiments they may be formed integrally as one piece having bothfunctions. The present inventors prefer the two-piece, separableembodiment because it allows for certain cleaning, assembly andpackaging advantages, that latter of which will be described infollowing paragraphs.

This embodiment also shows a fixed eyelet (109) for receiving a rope,tie-down or bungee cord, which may in other embodiments be replaced witha swiveling eyelet, a clip, or other means for attaching to a rope, cordor tie-down. At the opposite ends of the clamp (100) from the eyelet(109) are the clamping ends (105, 106) of the jaws (101, 102), whichpresent juxtapositioned to each other two clamping surfaces (107) whichwill be described in greater detail in the following paragraphs.

Referring now to FIG. 1 b, the exemplary embodiment of FIG. 1 a is shownin a closed and clamping position after the edge of a sheet material(110) has been received into its clamping area (107). To operate theclamp from the open position of FIG. 1 a to the closed position of FIG.1 b, the sheet material (110), such as a tarp or a sail or othermaterial, is maneuvered into the clamping area (107), and the actuatingscrew (104) is turned to close the jaws (101, 102) until they makecontact with the material (110) and place it into a frictional bindbetween the jaws, thereby securing the clamp to the material andallowing the eyelet to be used to attach a tie-down means to thecombination.

Turning now to FIG. 2, an exploded view of the three components of theexemplary embodiment of FIGS. 1 a and 1 b is shown. More details of theclamping area (107) is shown in an upper clamping surface (107 b) and alower clamping surface (107 a), which in this exemplary embodiment formnesting concave and convex concentric protuberances as shown. Forexample, a protruding (convex) ring shape on one surface will mate intoa recessed (concave) ring shape in the opposite, juxtapositionedsurface. The two clamping surfaces are designed with dimensions suchthat, when the clamp is fully closed, there may be a gap or spacebetween opposing surfaces to accommodate a thickness of the tarpmaterial.

Please note that the circular shapes of this clamping surface patternprovide an advantage over the devices currently available which providelinear, jagged teeth in their clamping surfaces. When the sheet materialis clamped, and when a rotational, twisting force is applied to theclamp, this embodiment will present no harsh or sharp edges to damagethe sheet material. Further, the circular clamping protuberances allowfor some slippage rotationally, while still maintaining a grip to keepthe clamp from pulling away from the edge of the tarp.

Other nesting shape combinations may be adopted for other embodiments,such as semi-circular protuberances having rounded or smoothed ends, andoval shaped protuberances (having no ends, of course).

To assemble, the clamp (100), the top jaw is maneuvered (312) so thatthe top hinge portion (103 b) of the top jaw member (101) is receivedinto the lower hinge portion (103 a) of the lower jaw member (102) toform a hinge (103), and then the actuating screw (104) is installed(310) through an orifice (108 b) in the top jaw (101) and threaded intoa corresponding orifice (108 a) in the lower jaw (102). The actuatingscrew preferably has a handle (301) to facilitate operation by hand, aretention portion (302), and a threaded shank (303), all of which willbe described in further detail in the following paragraphs.

As the actuating screw is continued to be threaded into the orifice (108a) of the lower jaw, it comes in contact with an upper surface of theupper jaw (101) and begins to force the jaws towards each other, therebybeginning to close the clamp. If a sheet material is present between theclamping surfaces (107 a, 107 b), then as the clamp is further closed,the sheet material is bound and crimped by the mating opposing surfaces,and becomes secured captured by the clamp.

Hinge shoulders (201 a, 201 b) may be provided in order to cause theends of the jaws near the hinge to be held further apart than the edgesof the clamps farthest away from the hinge. As the screw is rotated toclose the jaws, the motion of the jaws relative to each other will causethe edges of the clamping surface farthest away from the hinge tocontact and bind the sheet material first, prior to the portions of theclamping surface which are closer to the hinge beginning to bind thetarp. Then, as the screw is rotated further, the jaws are drawn closerto each other in their center area, which causes the jaws to flex andbow towards each other, thereby closing the clamping surfaces togethernearer the hinges.

Referring now to FIG. 3, the upper jaw (101) is shown (c) from a topview, in which the orifice (108 b) is preferably formed as a slotted oroval-shaped void in the upper jaw (101). A corresponding cross-sectionalview (b) shows a preferred embodiment of that orifice which includes aninterior retention groove or annular channel (311 a) formed around theperiphery of the orifice (108 b). The actuating screw (104) is shown (a)having a detente shoulder (304), a threaded shank portion (303), and apreferred retention area (304) which has a retention shoulder (311 b)formed around it, suitably sized to be received in the retention groove(311 a) of the orifice (108 b) when the screw (104) is received (310)through the orifice (108 b) during assembly and operation.

During assembly, the retention means (311 a, 311 b) is not yet engagedas the screw is not yet fully installed in the assembly. As the threadsengage the lower orifice (108 a) in the lower jaw member (102), it ispulled through the upper orifice (108 b) until the retention shoulder(311 b) reaches the upper material of the orifice (108 b) rim. Then, asthe screw is further turned, the retention shoulder (311 b) iscompressed and forced into the orifice (108 b), eventually finding ahome resting position by expanding into the retention groove (311 a).Now, the screw (104) is captured by the upper jaw (101), and free torotate clockwise or counterclockwise to tighten or open the clamp,respectively.

Turning to FIG. 4, an optional advanced aspect of the clamping surfaces(107 a, 107 b) is shown. FIG. 4( a) is a top view of a clamp assembly(100) as previously described, having clamp jaw ends (105, 106) on theopposite end of the clamp (100) from the hinge (103). As shown incut-away view (400) in FIG. 4( b), the upper clamping surface (107 b)has a number of protuberances which nest downwards into correspondingrecesses in the lower clamping surface (107 a). While these nestingprotuberances and recesses provide a good clamping surface for a sheetmaterial, please note a further enhancement to the clamping structure inwhich one surface (the upper surface in this case) is slightly convex inshape (bowing downwards) such that the inner-most protuberances willcontact the sheet material before the outermost protuberances. Similarlyand correspondingly, the other surface (the lower surface in this case)is slightly concave in shape (also bowing downwards) such that the innerrecesses are somewhat lower than the outer recesses. The structures canbe reversed, of course, while maintaining the particular functionaladvantage of pre-loading the clamp as is it closed by biting on theinnermost protuberances first, and the outermost protuberances last.During usage, if the sheet material and the clamp are pulled in a mannerthat would try to remove the material from the clamp in a directionthrough length of the jaws (e.g. a force from the eyelet towards theclamping surfaces), the flexing action of the pre-loaded jaws will causethe pulling motion to increase the clamping force in the areas of theclamping surfaces towards the hinge.

The clamping surfaces as shown in FIGS. 3 and 4 illustrate twoconcentric circles, which may be substituted for other non-linear shapes(e.g. curves, ovals, etc.) which have rounded or smoothed edges, andwhich may be greater in number (e.g. greater than two), or which may beas few as one (e.g. just a concave and a convex mating surface).

Another advantage of this particular embodiment is that it can beassembled and packaged in a single operation. For example, if one ormore clamps are attached to a sheet of card stock for display and retailsales, the card stock can be pre-cut to include a hole for eachactuating screw. Then, the lower jaw is placed beneath the card stockwith the lower orifice (108 a) aligned with the hole in the card stock,the upper jaw is positioned in alignment with the lower orifice and cardstock hole above the lower jaw with the card stock between the jaws, andthe actuating screw is then installed normally plus it passes throughthe card stock. As the screw snaps into place, the assembly of the clampis completed simultaneously as the packaging of the product iscompleted.

CONCLUSION

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof, unless specifically stated otherwise.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

It will be readily recognized by those skilled in the art that theforegoing example embodiments do not define the extent or scope of thepresent invention, but instead are provided as illustrations of how tomake and use at least one embodiment of the invention. The followingclaims define the extent and scope of at least one invention disclosedherein.

What is claimed is:
 1. A sheet material clamp comprising: a lowerclamping jaw having a hinge end and a clamping surface end; an upperclamping jaw having a hinge end and a clamping surface end; a partialknuckle disposed on at least one of the hinge ends; a pin disposed on atleast one of the hinge ends, reversibly snapped into the partial knuckleto form a dead hinge between the lower and upper clamping jaws; a firstorifice formed in the lower clamping jaw having a threaded interiorwall; a second orifice formed in the upper clamping jaw having anon-threaded interior wall and having a retention groove formed aroundthe non-threaded interior wall; and an actuating screw having a head anda threaded shank portion, and having a retention shoulder formed betweenthe head and the threaded shank, wherein the threaded shank mates withthe threaded interior wall of the first orifice of the lower clampingjaw, and wherein the retention shoulder is received within the retentiongroove; thereby capturing the actuating screw in the upper clamping jawwhen threaded into the lower clamping jaw such that a degree of openingor closing of the jaw is set by a number of turns on the actuating screwas defined by a distance between the threaded interior wall and theretention shoulder.
 2. The sheet material clamp as set forth in claim 1wherein the second orifice is formed in a slotted or oval shape wherebythe actuating screw is allowed to pass through the upper jaw at an angleother than perpendicularly through a thickness of the upper jaw as thejaws assume various angles of relationship to each other during clampclosing and opening.
 3. The sheet material clamp as set forth in claim 1wherein the head comprises a knurled handle.
 4. The sheet material clampas set forth in claim 1 wherein the head comprises a bolt head or ascrew head.